The common-used bathroom shower device usually comprises three main parts: a shower head, a shower-divert device and a spout. The shower-divert device connects two source water pipes: one for the hot-water and the other for the cold, and its function is expected to be able to not only shut off, but also divert the water, either to the shower head or to the spout. Such shower-divert devices in the present market could be divided into two main varieties: double-knobbed and uni-handled. Though much easier to operate, the later has its defects such as:
a) it is much more expensive;
b) it is so complex in structure that when inoperative, it has to be repaired by professionals, which means higher maintenance costs;
c) most uni-handled shower-diverts device are made of fine porcelain which is easier to be damaged by low quality water, in this case, the conventional rubber seal is not only much cheaper, but also much safer; and,
d) since it has been on the market for a very short time, its components are under standardized and it may be difficult to find repair parts.
It will be very useful if a high control efficiency double-knobbed shower divert device could be developed.